Central nervous system labelling composition for intranasal administration and labelling method and screening method using central nervous system labelling composition for intranasal administration

ABSTRACT

There is provided a central nervous system labelling composition for intranasal administration for the purpose of labelling the central nervous system from the olfactory epithelium by way of the olfactory bulb and by means of intranasal administration. Additionally, there is provided a method of non-invasively labelling the central nervous system by way of an administration route that entails little transferability to the entire body. Furthermore, there is provided a screening method using a central nervous system labelling composition for intranasal administration. A central nervous system labelling composition for intranasal administration is characterized by labelling the central nervous system from the olfactory epithelium by way of the olfactory bulb and by means of intranasal administration and by containing at least one compound expressed either by the general formula (1) or the general formula (2) shown below as effective component:

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/JP2010/007465, filed Dec. 24, 2010, which claims the benefit ofJapanese Patent Application No. 2009-296329, filed Dec. 25, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a central nervous system labellingcomposition for intranasal administration for the purpose of labellingthe central nervous system from the olfactory epithelium by way of theolfactory bulb and by means of intranasal administration, a labellingmethod using a central nervous system labelling composition forintranasal administration and also a screening method using a centralnervous system labelling composition for intranasal administration.

2. Description of the Related Art

A central nervous system labelling composition is transferable to thecentral nervous system of a living body so as to localize at aparticular site of the central nervous system. Thus, it is possible toobserve the activity of living central nervous system at a cellular ormolecular level and diagnose a disease of a central nervous system byvisualizing the state of localization of the central nervous systemlabelling composition, using an appropriate external observation unit.

Fluorine-18 label fluorodeoxy glucose (FDG) is one of the compounds thatare being used for central nervous system labelling. FDG can obtaininformation useful for diagnosis of brain tumor by visualizing the stateof localization thereof in the brain tumor, if any, in the centralnervous system by means of positron emission tomography (PET).

The compound disclosed in International Publication No. WO2007/063950gazette is a near-infrared fluorescent dye having affinity for amyloid βprotein. Information useful for diagnosis of the Alzheimer's disease canbe obtained by visualizing the site of central nervous system whereamyloid β protein is deposited by way of a near-infrared fluorescenceobservation unit.

U.S. Patent Application Publication No. 2006/0193776 gazette discloses acompound screening method for central nervous systems using zebrafish.According to the patent literature, a dye compound transfers to thebrain of an immature zebrafish but not to its central nervous system tendays after fertilization probably because of formation of a blood-brainbarrier.

SUMMARY OF THE INVENTION

The transferability of a compound to the brain is limited due to ablood-brain barrier (BBB) or a blood cerebrospinal fluid barrier (BCSFB)and there are many compounds that can transfer into an ordinary tissuebut not into the brain. For this reason, there has been a demand forcentral nervous system labelling compounds that can clearly label thecentral nervous system without being affected by a BBB or a BCSFB.

Any known central nervous system labelling composition is normallyadministered by intradermal, intraabdominal, intravenous, intraarterialor cerebrospinal fluid injection. Further, when a developed chemicalsubstance can be distributed also to the entire body other than thecentral nervous system by way of the circulatory system, it is requiredto deliberately take safeness relative to anaphylactic shock, heartfailure, liver function failure, kidney function failure, skin disorder,respiratory disorder and so on into consideration.

The problem to be solved by the present invention is to provide acentral nervous system labelling composition that can be administered byway of a route that neither gives rise to a transfer to the entire bodynor significantly affects the living body.

As a result of the intensive research efforts made by the inventors ofthe present invention to solve the above identified problem, theinventors found a central nervous system labelling composition forintranasal administration that can label the central nervous system fromthe olfactory epithelium by way of the olfactory bulb and by means ofintranasal administration and that transfers only to a small extent tothe entire body by way of the circulatory system. The present inventionis based on this finding.

Namely, the present invention provides a central nervous systemlabelling composition for intranasal administration for the purpose oflabelling the central nervous system from the olfactory epithelium byway of the olfactory bulb and by means of intranasal administration,characterized by containing at least one compound expressed either bythe general formula (1) or the general formula (2) illustrated below aseffective component:

(in which general formula (1) R₁ represents an alkyl group, each of R₃through R₆ independently represents a hydrogen atom, an alkyl group, anaryl group, an alkoxy group, a carboxylic acid group, a sulfonic acidgroup, a heterocyclic group, an amino group or a halogen atom, of whichR₅ and R₆ may be bonded to each other to form a ring, X₁ ⁻ represents ananionic group and A represents a general formula (3) or a generalformula (4) illustrated below),

(in which general formula (2) each of R₁₁ through R₁₅ independentlyrepresents a hydrogen atom or an alkyl group and X₂ ⁻ represents ananionic group),

(in which general formula (3) R₂ represents an alkyl group and each ofR₇ through R₁₀ independently represents a hydrogen atom, an alkyl group,an aryl group, an alkoxy group, a carboxylic acid group, a sulfonic acidgroup, a heterocyclic group, an amino group or a halogen atom, of whichR₇ and R₈ may be bonded to each other to form a ring) and (in whichgeneral formula (4) Y represents an alkyl group).

A central nervous system labelling composition for intranasaladministration according to the present invention labels the centralnervous system from the olfactory epithelium by way of the olfactorybulb and by means of intranasal administration. Therefore, the presentinvention enables to highly precisely and easily evaluate and analyzethe morphology of the central nervous system and the state of the cellsthereof while reducing the influence to the living body that arises asthe composition is distributed to the tissues of the entire body by thecirculatory system.

Since a central nervous system labelling composition for intranasaladministration according to the present invention transfers with timefrom the olfactory epithelium to the central nervous system by way ofthe olfactory bulb as a result of intranasal administration, it ispossible to visualize how the olfactory nerve cells are linked bymonitoring the state of localization of the labelling composition in thetransfer process.

Additionally, when the transfer mechanism of a compound to the centralnervous system antagonizes the transfer mechanism of a central nervoussystem labelling composition for intranasal administration according tothe present invention, the central nervous system labelling process of acentral nervous system labelling composition for intranasaladministration according to the present invention is influenced by thecoexisting compound. Then, it is possible to find out the possibility oftransfer of the compound to the central nervous system after theintranasal administration by detecting the influence. In other words, itis possible to screen out a drug that tends to transfer to the centralnervous system as a result of intranasal administration by using acentral nervous system labelling composition for intranasaladministration according to the present invention.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a labeled image of the central nervous system observed inExample 1.

FIG. 1B is a labeled image of the central nervous system observed inExample 1.

FIG. 1C is a labeled image of the central nervous system observed inExample 1.

FIG. 2 is a labeled image of the central nervous cell observed inExample 1.

FIG. 3A is a labeled image of the central nervous system observed inExample 2.

FIG. 3B is a labeled image of the central nervous system observed inExample 2.

FIG. 3C is a labeled image of the central nervous system observed inExample 2.

FIG. 4A is a labeled image of the central nervous cell observed inExample 2.

FIG. 4B is a labeled image of the central nervous cell observed inExample 2.

FIG. 4C is a labeled image of the central nervous cell observed inExample 2.

FIG. 5 is an observation image of the zebrafish observed in ComparativeExample 1.

FIG. 6A is a labeled image of the central nervous system observed inExample 3.

FIG. 6B is a labeled image of the central nervous system observed inExample 3.

FIG. 6C is a labeled image of the central nervous system observed inExample 3.

FIG. 7 is a labeled image of the central nervous cell observed inExample 3.

DESCRIPTION OF THE EMBODIMENTS

Now, the present invention will be described below by way of specificembodiments thereof. However, it should be noted that the embodimentsdescribed below are simply exemplar embodiments and by any means do notlimit the scope of the present invention.

A central nervous system labelling composition for intranasaladministration that is the first embodiment of the present invention isa central nervous system labelling composition for labelling the centralnervous system from the olfactory epithelium by way of the olfactorybulb by means of intranasal administration, characterized by containingat least one compound expressed by the general formula (1) or (2)illustrated below.

in which general formula (1) R₁ represents an alkyl group, each of R₃through R₆ independently represents a hydrogen atom, an alkyl group, anaryl group, an alkoxy group, a carboxylic acid group, a sulfonic acidgroup, a heterocyclic group, an amino group or a halogen atom, of whichR₅ and R₆ may be bonded to each other to form a ring, X₁ ⁻ represents ananionic group and A represents a general formula (3) or a generalformula (4) illustrated below,

in which general formula (2) each of R₁₁ through R₁₅ independentlyrepresents a hydrogen atom or an alkyl group and X₂ ⁻ represents ananionic group,

in which general formula (3) R₂ represents an alkyl group and each of R₇through R₁₀ independently represents a hydrogen atom, an alkyl group, anaryl group, an alkoxy group, a carboxylic acid group, a sulfonic acidgroup, a heterocyclic group, an amino group or a halogen atom, of whichR₇ and R₈ may be bonded to each other to form a ring and in whichgeneral formula (4) Y represents an alkyl group. ‘*’ represents thebinding site.

Examples of alkyl group in R₁ through R₂ in the general formulas (1) and(3) non-limitatively include a methyl group, an ethyl group, a propylgroup and a butyl group. The group may further have a substituentprovided that the group does not remarkably damage the storage stabilityof a dye compound according to the present invention.

Examples of alkyl group in R₃ through R₁₀ non-limitatively include amethyl group, an ethyl group, a propyl group and a butyl group.

Examples of aryl group in R₃ through R₁₀ non-limitatively include aphenyl group and a naphthyl group.

Examples of alkoxy group in R₃ through R₁₀ non-limitatively include amethoxy group, an ethoxy group, a propoxy group and a butoxy group.

Examples of heterocyclic group in R₃ through R₁₀ non-limitativelyinclude a pyridyl group, a pyradyl group and a morpholinyl group.

Examples of amino group in R₃ through R₁₀ non-limitatively include anunsubstituted amino group, a monosubstituted amino group such as anN-methylamino group or an N-ethylamino group and a disubstituted aminogroup such as an N,N-dimethylamino group, an N,N-diethylamino group oran N,N-methylpropylamino group.

Examples of halogen atom in R₃ through R₁₀ non-limitatively include afluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of ring formed as R₅ and R₆ and/or R₇ and R₈ are bonded to eachother include a phenyl group.

Examples of anionic group in X₁ ⁻ non-limitatively include a halogen ionsuch as a chloride ion, a bromide ion or an iodide ion, an inorganicacid ion such as a sulfuric acid ion or a phosphoric acid ion and anorganic acid ion such as an acetate ion.

Examples of alkyl group in Y in the general formula (4) non-limitativelyinclude a methyl group, an ethyl group, a propyl group and a butylgroup.

Examples of alkyl group in R₁₁ through R₁₅ in the general formula (2)non-limitatively include a methyl group, an ethyl group, a propyl groupand a butyl group. The group may further have a substituent providedthat the group does not remarkably damage the storage stability of a dyecompound according to the present invention.

Examples of anionic group in X₂ ⁻ non-limitatively include a halogen ionsuch as a chloride ion, a bromide ion or an iodide ion, an inorganicacid ion such as a sulfuric acid ion or a phosphoric acid ion and anorganic acid ion such as an acetate ion.

Dye compounds expressed by the general formula (1) or (2) that can beused for the purpose of the present invention are commercially availableand can be synthesized by a known method.

Preferable exemplar dye compounds expressed by the general formula (1)or (2) are non-limitatively listed below.

The concentration of the compound contained in the central nervoussystem labelling composition for intranasal administration according tothe present invention is not particularly limited so long as the centralnervous system can be detected and may be adjusted according to thetarget site and the actual compound to be used. Normally, the compoundis used with a concentration of not less than 0.001 ng/mL and not morethan 100 μg/mL, preferably with a concentration of not less than 0.001ng/mL and not more than 10 μg/mL, more preferably with a concentrationof not less than 0.001 ng/mL and not more than 5 μg/mL.

At least one compound expressed by the general formula (1) or (2) isdissolved into an appropriate solvent so as to be used for a centralnervous system labelling composition for intranasal administrationaccording to the present invention. The solvent to be used is preferablyan aqueous solvent showing a strong affinity for living bodies, althoughthe solvent is not subjected to any particular limitations so long asthe solvent does not adversely affect living bodies. Specific examplesof solvent include water, isotonic sodium chloride solution, buffersolutions such as phosphate buffer solution (PBS) and Tris buffersolution, alcoholic solvents such as methanol, ethanol, isopropanol,butanol, ethylene glycol, glycerin and so on, organic solvents such asN,N-dimethylsulfoxide (to be abbreviated as “DMSO” hereinafter) andN,N-dimethylformamide (to be abbreviated as “DMF” hereinafter), cellculture media such as D-MEM (Dulbecco's Modified Eagle Medium and HBSS(Hank's Balanced Salt Solutions) and infusion solutions such as lactatedRinger's solution. The solvent desirably contains 50% water. Two or morethan two such solvents may be mixed for use.

The method of preparing a central nervous system labelling compositionfor intranasal administration according to the present invention is notsubjected to any particular limitations. For example, a dense solutionof a compound prepared by dissolving the compound in a solvent selectedfrom the above-listed ones may be diluted for use. When the compound ispoorly soluble to water, the compound may be dissolved into anappropriate solvent and then, the solution may be diluted by purifiedwater. Particularly preferable solvents include methanol, ethanol andDMSO.

If necessary for controlling the salt concentration and the pH value tomake the solution adapted for living bodies, an additive or one or morecombined additives may be added to a central nervous system labellingcomposition for intranasal administration according to the presentinvention.

The additive to be used for the purpose of the present invention is notsubjected to any particular limitations so long as the additive does notadversely affect a central nervous system labelling composition forintranasal administration according to the present invention. Examplesof additive that can be used for the purpose of the present inventioninclude moisturizing agents, surface tension adjusting agents, viscosityenhancing agents, salts such as sodium chloride, various pH adjusters,pH buffering agents, antiseptics, antibacterial agents, sweeteningagents and perfumes.

pH adjusters to be used for the purpose of the present invention arepreferably adapted for adjusting the pH value of the solution to 5through 9. Examples of pH adjusters non-limitatively includehydrochloric acid, acetic acid, phosphoric acid, citric acid, malicacid, sodium hydroxide, sodium hydrogen carbonate and so on.

(Labelling Targets)

Examples of species in which the central nervous system can be labeledfrom the olfactory epithelium by way of the olfactory bulb by a centralnervous system labelling composition for intranasal administrationaccording to the present invention non-limitatively include vertebratessuch as bony fishes (Osteichthyes) including Takifugu rubripes, Takifuguniphobles, Tetraodon nigroviridis, Oryzias latipes, zebrafish and so on,amphibians including Xenopus laevis and so on, birds including Gallusgallus domesticus, quail and so on, small animals such as rat, mouse,hamster and so on, large animals such as goat, pig, dog, cat, cattle,horse and so on, primates such as monkey, chimpanzee, human and so on.In particular, the central nervous system of any of such living bodiescan be dyed alive. Human may be omitted from the above species.

Examples of central nervous system that can be labeled by using acentral nervous system labelling composition for intranasaladministration according to the present invention include centralnervous systems composed of cerebrum, mesencephalon, cerebellum,diencephalons, medulla oblongata, spinal cord, optic tract, superiorcolliculus, pituitary gland, tectospinal tract, reticular formation andso on, such, tissues of such systems in a diseased state, neoplastictissues due to disease, cancer tissues and so on. If central nervoussystems that are different from the above-described ones exist becauseof difference of species, developmental stage, abnormal developmentand/or disease, such tissues may also be included.

Cells in the central nervous system non-limitatively include nervecells, oligodendrocytes, Schwann cells, Purkinje cells, amacrine cells,retinal ganglion cells (RGC), cone cells, astrocytes, granule cells,glial cells, tumor cells thereof and undifferentiated cells (stem cells)thereof.

An administration route that is the second embodiment of the presentinvention is characterized in that a central nervous system labellingcomposition for intranasal administration as defined above isadministered to the inside of the nasal cavity of a living body. As acentral nervous system labelling composition for intranasaladministration according to the present invention is administered to theinside of the nasal cavity of a living body, the central nervous systemcan be labeled with time from the olfactory epithelium by way of theolfactory bulb. In other words, olfactory receptor cells are labeledimmediately after the administration, then the olfactory bulb andsubsequently the cerebrum (Telencephalon) are sequentially labeled. Itis possible to identify a labeled site and dye cells there to see theirshapes as a function of the time elapsed after the intranasaladministration.

While the method of administering a central nervous system labellingcomposition for intranasal administration according to the presentinvention to the inside of the nasal cavity of a living body is notsubjected to any particular limitations, for instance, a method ofbringing the composition into contact with the nasal mucosa byintranasally spraying or applying it may be employed. When a centralnervous system labelling composition for intranasal administrationaccording to the present invention is to be administered to an animal,the mode and the quantity of administration should be appropriatelyselected according to the weight and the conditions of the animal.

A method of acquiring information by visualizing a label that is thethird embodiment of the present invention is characterized in that themethod includes a process of dyeing the central nervous system of aliving body from the olfactory epithelium by way of the olfactory bulb,using a central nervous system labelling composition for intranasaladministration according to the present invention. In other words, themethod is characterized by intranasally administering a central nervoussystem labelling composition for intranasal administration according tothe present invention, irradiating light of an excitation wavelengthonto an observation site after the elapse of a predetermined timeperiod, observing the generated fluorescence of a longer wavelength andforming an image thereof.

A central nervous system labelling composition for intranasaladministration according to the present invention can label any of thecranial nerves including the olfactory nerve. A specific labellingmethod that can preferably be used for the purpose of the presentinvention is a method of using a dye or a probe labeled by aradionuclide. Dyeing a cranial nerve is preferable because it can imagethe distribution and the orientation of the neural tissue of theperipheral nervous system that is connected to that of the centralnervous system.

For the purpose of the present invention, to dye cells to see theirshapes means that to dye at least one type of cells existing in thecentral nervous system to enable to determine the cell morphology ofeach type, for example, by means of fluorescence or the like.

A central nervous system labelling composition for intranasaladministration according to the present invention is preferably afluorescent compound having fluorescent properties. Compounds expressedby any the above-described formulas (5) through (7) also belong to sucha category. A method of labelling the olfactory neural circuit or thecentral nervous system using a central nervous system labellingcomposition for intranasal administration according to the presentinvention includes intranasally administering a central nervous systemlabelling composition for intranasal administration according to thepresent invention, irradiating light of an excitation wavelength onto anobservation site after the elapse of a predetermined time period,observing the generated fluorescence of a longer wavelength than theexcitation wavelength and forming an image thereof. Thus, cellmorphology information of the labeled site can be obtained.

The observation method to be used for the purpose of the presentinvention is not subjected to any particular limitations as long as itdoes not cause any effect to the observed central nervous system, and itcan be a method of capturing the state or the change of a sample of aliving body as image. For example, it may be a method of irradiatingvisible light, near-infrared rays or infrared rays to the centralnervous system and observing it by means of a camera, a CCD or a lasermicroscope; a method of irradiating excitation light from an excitationlight source onto a sample of a living body typically by means of afluorescent endoscope and observing emitted fluorescence of the sampleof a living body directly or by way of a fluorescent microscope, afluorescent endoscope, a confocal fluorescent microscope, a multi-photonexcitation fluorescent microscope; narrow band imaging (NBI); optialcoherence tomography (OCT); or a soft X-ray microscope.

While the wavelength of light to be used for excitation for the purposeof the present invention is not subjected to any particular limitations,the wavelength may vary as a function of the dye compound to be usedthat is expressed by the general formula (1) or (2). Again, thewavelength is not subjected to any particular limitations so long as thedye compound that is expressed by the general formula (1) or (2) isexcited and caused to emit fluorescence efficiently. It is normally 200through 1,010 nm, preferably 400 through 900 nm, more preferably 480through 800 nm. When rays in the near-infrared region are employed,normally a wavelength of 600 through 1,000 nm, preferably a wavelengthof 680 through 900 nm is employed because light of such a wavelength canadvantageously be transmitted through a living body.

The fluorescence excitation light source to be used for the purpose ofthe present invention is not subjected to any particular limitations andvarious laser sources may selectively be employed. Light sources thatcan be used for the purpose of the present invention include dye lasers,semiconductor lasers, ion lasers, fiber lasers, halogen lamps, xenonlamps and tungsten lamps. It is also possible to obtain a preferableexcitation wavelength and/or detect only fluorescence by using any ofvarious optical filters.

Thus, it is possible to detect a light emitting site of an individualliving body by irradiating the living body and imaging the centralnervous system thereof in a state where the central nervous system emitslight in the inside. Furthermore, the central nervous system can beobserved in a more detailed manner by combining a bright field imageobtained by irradiating visible light and a fluorescent image obtainedby irradiating excitation light by an image processing unit. The use ofa confocal microscope is preferable because optical slice images can beobtained by means of confocal microscope. A multi-photon excitationfluorescent microscope can preferably be employed to observe the insideof a tissue because the microscope can get into a deep spot and shows ahigh spatial resolution.

A central nervous system labelling composition for intranasaladministration according to the present invention can be used as a probelabeled by a radionuclide. The type of radionuclide to be used forlabelling is not subjected to any particular limitations and aradionuclide of an appropriate type may be selected according to themode of operation thereof. More specifically, in the case of observationby PET, examples of radionuclide include positron emission radionuclidessuch as ¹¹C, ¹⁴C, ¹³N, ¹⁵O, ¹⁸F, ¹⁹F, ⁶²Cu, ⁶⁸Ga and ⁷⁸Br, of which ¹¹C,¹³N, ¹⁵O and ¹⁸F are preferable and ¹¹C and ¹⁸F are particularlypreferable. In the case of observation by SPECT, examples ofradionuclide include γ-ray emission radionuclides such as ⁹⁹mTc, ¹¹¹In,⁶⁷Ga, ²⁰¹Tl, ¹²³I and ¹³³Xe, of which ⁹⁹mTc and ¹²³I are preferable.When observing an animal other than human, a radionuclide having a longhalf life such as ¹²⁵I can be used. In the case of observation by GREI,¹³¹I, ⁸⁵Sr and ⁶⁵Zn can be employed.

The central nervous system labelling composition for intranasaladministration that is labeled by a radionuclide can be imaged typicallyby autoradiography, positron emission tomography (PET) using a positronemission radionuclide, single photon emission computed tomography(SPECT) using any of various γ-ray emission radio nuclides or the like.Alternatively, the composition may be detected by nuclear magneticresonance imaging (MRI) that utilizes MR signals originating from nucleiof fluorine atoms or ¹³C. Furthermore, the composition can be imaged bymeans of a Compton camera (GREI) capable of simultaneously imaging aplurality of molecules that is regarded as a next generation moleculeimaging apparatus. It is also possible to quantify a probe for a centralnervous system by means of a liquid scintillation counter, an X-rayfilm, or an imaging plate.

Additionally, it is possible to observe the blood (or urine or feces)concentration of a central nervous system labelling composition forintranasal administration that is labeled by a radioactive isotope suchas ¹⁴C by means of accelerator mass spectrometry (AMS) in order toobtain pharmacokinetic information on the labeled substance that isunchanged and/or the metabolite thereof, such as the area under theblood concentration-time curve (AUC), the elimination half life (T½),the maximum drug concentration (Cmax), the maximum drug concentrationtime (Tmax), the volume of distribution, the first pass effect, thebioavailability and the fecal and urinary excretion rate.

The radionuclide may be contained in or bonded to a compound expressedby the general formula (1) or (2). Specific examples of compounds havingor bonded to a radionuclide for the purpose of the present inventioninclude compounds expressed by the general formulas (5) (7) that containa radionuclide or to which a radionuclide is bonded.

For the purpose of the present invention, any popular labelling methodusing a radionuclide can be employed without limitations. At least partof the elements constituting a compound expressed by the general formula(1) or (2) may be substituted by or bonded to a radionuclide.

When a compound expressed by the general formula (1) or (2) is labeledby a radionuclide, the compound preferably shows a level ofradioactivity of about 1 to 100 μCi per 1 mM.

Then, the dose of the central nervous system labelling composition forintranasal administration to be used is not subjected to any particularlimitations and may be selected according to the type of the compoundand that of the radionuclide used for the labelling.

As the fourth embodiment of the present invention, a central nervoussystem labelling composition for intranasal administration can beutilized for diagnosis of brain tumor/brain infarction and fordiagnosis/therapy/operation using a cerebral endoscope (fiberscope).

A central nervous system labelling composition for intranasaladministration according to the present invention can be used as meansfor uniquely and selectively dyeing the site of a substance to beexamined that seems to be an ailing cellular tissue or tumor during aneurosurgical operation and reliably recognizing the difference fromnormal cells or for observing the change in a tissue due to a disease.

A central nervous system labelling composition for intranasaladministration according to the present invention can label a centralnervous system without requiring a highly invasive operation of exposingthe central nervous system or injecting a dye into the central nervoussystem or into a tissue connected to the central nervous system.Therefore, the composition can find applications in diagnostic agentsthat exploit the labelling effect for identifying a labeled site.

Its applications non-limitatively include diagnostic agents forexamining the function of the brain and those for diagnosing a braindisease.

The brain diseases that can be diagnosed by such diagnostic agentsnon-limitatively include Parkinson's disease, Alzheimer's disease,Huntington's chorea, motor neuron disease, tauopathy, cortico basaldegeneration (CBD), depressive disorder, epilepsy, migraine,spinocerebellar degeneration (SCD), brain tumor, intracranial hemorrhageand brain infarction.

Specific examples of the fourth embodiment of the present invention willbe listed below.

(1) Functional Neuroimaging/Brain Mapping

A central nervous system labelling composition for intranasaladministration according to the present invention can be used as probefor functional neuroimaging and brain mapping to replace conventionalfMRI, near-infrared functional neuroimaging and endogenous signalimaging. A central nervous system labelling composition for intranasaladministration according to the present invention transfers to theinside of the central nervous system, moving through axons of neuronsand synaptic clefts. On the other hand, the fluorescent characteristicsof a central nervous system labelling composition for intranasaladministration according to the present invention change according tomutually dependent molecules of living body and the solvent environment.Therefore, the changes in the activity of cranial nerve cells can bedetected by detecting the changes in the fluorescent characteristics.

(2) Olfactory Information Processing/Olfactory Recognition Researches

Animals of many species utilize the olfactory sensation for their eatingbehaviors, danger avoidance behaviors, reproductive behaviors and otherbehaviors that are indispensable for survival. While there have beenrapid advancements in research on the olfactory sensation since thediscovery of the receptor gene family of the olfactory sensation, theneural circuit that governs odor-invoked behaviors such as enticedreactions to “favorite” odors and evasive reactions to “disgusting”odors has not been satisfactorily elucidated.

A central nervous system labelling composition for intranasaladministration according to the present invention can be used tovisualize the olfactory neural circuit of an animal and elucidate theconnections existing in it. It will be possible to draw an odor map ofthe olfactory bulb and identify the olfactory information transmissionpaths by making an odorant and a central nervous system labellingcomposition for intranasal administration according to the presentinvention coexist and identifying the olfactory neural circuit whosedyeability changes.

(3) Photosensitizer (Photodynamic Therapy: PDT)

A central nervous system labelling composition for intranasaladministration according to the present invention can be used asphotosensitizer. A photosensitizer is activated when irradiated withphotoactivating light and the photosensitizer itself or some otherchemical species (e.g., oxygen) are transformed into cytotoxic species,which by turn kills the target cells of the site irradiated with lightor reduces the reproductive potential thereof.

Therefore, a central nervous system labelling composition for intranasaladministration according to the present invention can be used fordiagnostic as well as therapeutic applications on the basis of a labelin the central nervous system.

A screening method, which is the fifth embodiment of the presentinvention, is characterized by detecting a compound acting in vivo onthe central nervous system by means of a central nervous systemlabelling composition for intranasal administration according to thepresent invention.

A central nervous system labelling composition for intranasaladministration according to the present invention can be used toevaluate in vivo the transferability to the central nervous system vianose of a compound to be screened out and the safety thereof by using azebrafish that is a small bony fish.

Zebrafish has been acknowledged in recent years as the third animalmodel, following mouse and rat, in the United States of America and inthe United Kingdom and it has been clarified that zebrafish's genomearrangement is 80% identical with that of human and the number ofzebrafish's genes is substantially same as the number of human genes andthat zebrafish's principal organs and tissues resemble to humancounterparts in terms of development and structure. Because the processof differentiation of zebrafish's parts (organs such as heart, liver,kidney and digestive system) from a fertilized embryo can be observedthrough its transparent body, it is particularly preferable to use azebrafish as animal model for screening.

For the purpose of the present invention, “detecting a compound actingon the central nervous system” means detecting if there is a compoundacting on the central nervous system or not and, if there is, itscharacteristics by observing the change, if any, in the labelability ofa central nervous system labelling composition for intranasaladministration according to the present invention when the compound tobe looked into (the compound to be screened out) is made to act on thecentral nervous system by using the central nervous system labellingcomposition for intranasal administration. As a specific example, ascreening method of bringing a compound to be screened out and azebrafish into contact with each other and observing the influence onthe ability of dyeing the brain of a zebrafish of an intranasallyadministered central nervous system labelling composition for intranasaladministration according to the present invention may be effective forsuch a purpose.

While the method for bringing a compound to be screened out into contactwith a zebrafish to be used for the purpose of the present invention isnot subjected to any particular limitations, it may be a method ofputting a compound to be screened out into the feeding water ofzebrafish for administration when the compound to be screened out iswater soluble, whereas it may be a method of dispersing a compound to bescreened out alone in the feeding water for administration, a method ofadministering it with a small amount of surfactant or DMSO, a method ofmixing it with a bait of zebrafish and orally administering it or anon-oral administration method such as injection when the compound to bescreened out is water insoluble. Preferably, a method of putting acompound to be screened out into the feeding water of zebrafish foradministration is employed from the viewpoint of easiness.

A compound to be screened out generically refers to a compound thatbiochemically acts on a living body. Such compounds non-limitativelyinclude drugs, organic compounds, therapeutic agents, investigationalproducts, agricultural chemicals, cosmetics, environment pollutingsubstances, endocrine disruptors and candidate compounds for such.Drugs, therapeutic agents and candidate compounds for such as describedabove refer to drugs for curing Parkinson's disease, Alzheimer'sdisease, Huntington's chorea, motor neuron diseases, tauopathy, corticobasal degeneration (CBD), depressive disorder, epilepsy, migraine,spinocerebellar degeneration (SCD), brain tumor, intracranialhemorrhage, brain infarction and so on and candidate compounds for suchas well as compounds that accelerate or suppress the transfer of any ofsuch compounds to the central nervous system via nose.

Additionally, such compounds include drugs for curing disorders of theolfactory sensation attributable to any of the above listed diseases andcandidate compounds for such.

Zebrafishes that can be used for the purpose of the present inventionare not limited to wild type zebrafishes but any of various diseasemodel zebrafishes can be used depending on the object of screening. Forinstance, disease model zebrafishes can be used to find out the effectsof new drug candidate compounds by observation and apply it to screeningout a therapeutic drug or a prophylactic drug.

Additionally, it is possible to evaluate the speed at which a compoundto be screened out transfers to the central nervous system of azebrafish via nose by observing the rate at which a dye dyes the brainof the zebrafish via nose when a central nervous system labellingcomposition for intranasal administration according to the presentinvention is intranasally administered and coexist with the compound tobe screened out.

A small bony fish can be used for a screening method according to thepresent invention. Small bony fishes that can be used for the screeningmethod of the present invention are not subjected to any particularlimitations. For example, such bony fishes include zebrafish, pufferfish, gold fish, killifish, giant rerio and so on. The use of small bonyfishes is preferable because they are very advantageous relative tomouse and rat in terms of growing speed and cost. Particularly, thegenome of zebrafish has been substantially completely deciphered and itis easy to feed and reproduce zebrafishes, which then can be distributedat low cost. Moreover, the basic structure of the principal organs andtissues of a zebrafish is formed in 48 through 78 hours afterfertilization. Therefore, the use of zebrafishes is particularlypreferable.

(Extrapolatability to Humans)

A central nervous system labelling composition for intranasaladministration according to the present invention is applicable tohumans. The extrapolatability thereof to humans can be confirmed byseeing the whole approximation given on the basis of recognition of thesimilarities and the differences of central nervous system betweenhumans and experiment animals. While several examples are given below,the present invention is by no means limited thereto.

(1) To confirm the similarities by dyeing the central nervous system ofhuman and that of a living biological sample other than human. Livingsamples other than human that can be used for the purpose of the presentinvention include mammals such as mouse, hamster, rat, guinea pig,rabbit, dog, pig, cat and monkey and bony fishes such as zebrafish.(2) To confirm the dyeability of the central nervous system by using animmobilized tissue slice of a human and that of a living biologicalsample other than human and thereby confirm that the human centralnervous system shows a dyeability similar to that of the central nervoussystem of the living biological sample.(3) To confirm the dyeability of the central nervous system by using animmobilized tissue slice of a human.

It is possible to confirm that a central nervous system labellingcomposition for intranasal administration according to the presentinvention is applicable to humans by conducting the above-describedthree confirming operations.

Alternatively, the extrapolability to humans can be confirmed byradioisotope-labelling a central nervous system labelling compositionfor intranasal administration according to the present invention,internally administering a minimal amount thereof to a human andensuring localization thereof to the central nervous system. Thistechnique is referred to as microdosing.

A still alternatively technique includes (1) identifying the targetliving molecules or the dyeing mechanism of a central nervous systemlabelling composition for intranasal administration according to thepresent invention by means of the central nervous system of a livingbiological sample other than human; (2) identifying the human livingmolecules homologous with the target living molecules or the dyeingmolecule mechanism; (3) introducing the human living molecules or thedyeing mechanism into an experiment animal by gene modification and (4)confirming that the central nervous system of the obtained experimentanimal is dyed by way of the introduced living molecule or dyeingmechanism.

A zebrafish can particularly preferably be used as biological sampleother than human. Many vertebrates preserve common features of centralnervous system very well from the anatomical, histological andbiochemical point of view very well as well as from the developmentpoint of view. Therefore, the use of zebrafishes provides a remarkableadvantage because the feeding cost is low and the amount of the compoundto be used can be very small if compared with the use of mice.Additionally, it has been proved that the central nervous system ofzebrafish shows a high degree of homology with that of human not only interms of shape but also in terms of molecular level. From the above, itis preferable to confirm the extrapolability to humans of a centralnervous system labelling composition for intranasal administrationaccording to the present invention by using zebrafishes.

EXAMPLES

The present invention will be described in greater detail by way ofexamples. However, it should be noted that the examples are only topromote understanding of the present invention and by no means limit thescope of the present invention. Unless noted otherwise, “%” refers to amass percent.

Example 1

Distilled water was added to a 1 mg/mL DMSO solution of compound 1 (asexpressed by the formula (5) above) to obtain a dye solution 1containing the compound 1 to a concentration of 200 ng/mL. 1 mL of thedye solution 1 and a 7-day-old (7 dpf) juvenile fish of zebrafish wereput into an arbitrarily selected well of a 24-hole multi plate(available from IWAKI) and left there for an hour. Thereafter, the dyesolution 1 in the well was removed and an operation of replacing it with1 mL of distilled water was repeated three times in ten minutes. Theelapsed time after the last solution replacing operation was measuredand the juvenile fish was taken out from the well when a predeterminedtime period had elapsed. The juvenile fish was buried in 5% lowmelting-point agarose gel on a glass slide to restrict any movement andthe dyed state of the central nervous system of the zebrafish wasobserved from a lateral side and the vertex by using fluorescentmicroscope (MZ16FA: available from Leica). The central nervous systemwas observed by means of a confocal microscope (Pascal Exciter:available from Zeiss). After the observation, the zebrafish was returnedinto the well and repeatedly observed thereafter at regular timeintervals.

As a result, a dyeability was confirmed that firstly the nasal cavity,then the olfactory bulb and finally the central nervous system weresequentially dyed as illustrated in FIGS. 1A, 1B and 1C.

Additionally, it was confirmed that nerve cells of the central nervoussystem were also dyed as illustrated in FIG. 2.

Example 2

Dye solution 2 whose concentration of the compound 2 is 500 ng/mL wasobtained by adding distilled water to 1 mg/mL DMSO solution of compound2 (as expressed by the formula (6) above). Operations same as those ofExample 1 were conducted except that the dye solution 2 was used inplace of the dye solution 1 to observe the central nervous system.

As a result, a dyeability was confirmed that firstly the nasal cavity,then the olfactory bulb and finally the central nervous system weresequentially dyed as illustrated in FIGS. 3A, 3B and 3C. Additionally, adyeability was confirmed that nerve cells of the central nervous systemwere also dyed as illustrated in FIGS. 4A, and 4B, which is an enlargedview of the inside of the frame in FIGS. 4A, and 4C, which is anenlarged view of the inside of the frame in FIG. 4B.

Comparative Example 1

Dye solution 3 whose concentration is 500 ng/mL was obtained by addingdistilled water to 1 mg/mL DMSO solution of fluorescein. Operations sameas those of Example 1 were conducted except that the dye solution 3 wasused in place of the dye solution 1 to observe the central nervoussystem.

As a result, no transfer with time of dyeability to the central nervoussystem was observed as illustrated in FIG. 5.

Example 3

Compound 3 (as expressed by the formula (7) above) was synthesized by amethod described in Japanese Patent Application Laid-Open No.2010-169677. Dye solution 4 whose concentration of the compound 3 is 500ng/mL was obtained by adding distilled water to 1 mg/mL DMSO solution ofcompound 3. Operations same as those of Example 1 were conducted exceptthat the dye solution 4 was used in place of the dye solution 1 toobserve the central nervous system.

As a result, a dyeability was confirmed that firstly the nasal cavity,then the olfactory bulb and finally the central nervous system weresequentially dyed as illustrated in FIGS. 6A, 6B and 6C. Additionally,the dyeability was confirmed that nerve cells of the central nervoussystem were also dyed as illustrated in FIG. 7.

The present invention provides a central nervous system labellingcomposition for intranasal administration that labels the centralnervous system of a living biological sample by way of a newadministration route and can highly sensitively image the shapes of thecells of the central nervous system. The labelling composition willbecome an indispensable material for researches of central nervoussystem regions and techniques of imaging central nervous systems. Italso enables to evaluate drug discoveries relating to the diseases ofcentral nervous system over time. Additionally, since a central nervoussystem labelling composition for intranasal administration according tothe present invention enables to conduct high precision screenings at ahigh throughput, an effective technical basis for dramatically promotingresearches on the central nervous system and making them industriallyviable will be provided.

The present application claims the benefit of Japanese PatentApplication No. 2009-296329, filed on Dec. 25, 2009, the disclosures ofwhich are partly incorporated herein by reference.

What is claimed is:
 1. A method of labeling a central nervous system ofa living body by dyeing from an olfactory epithelium by way of anolfactory bulb, the method comprising intranasally administering acentral nervous system labeling composition comprising a compound offormula (1):

where R₁ represents an alkyl group; each of R₃ through R₆ independentlyrepresents a hydrogen atom, an alkyl group, an aryl group, an alkoxygroup, a carboxylic acid group, a sulfonic acid group, a heterocyclicgroup, an amino group, or a halogen atom, of which R₅ and R₆ may bebonded to each other to form a ring; X₁ ⁻ represents an anionic group;and A represents a formula (4):

where Y represents an alkyl group; and * represents a binding site.
 2. Ascreening method for detecting in vivo a compound acting on a centralnervous system, the method comprising: intranasally administering acentral nervous system labeling composition comprising a compound offormula (1):

where R₁ represents an alkyl group; each of R₃ through R₆ independentlyrepresents a hydrogen atom, an alkyl group, an aryl group, an alkoxygroup, a carboxylic acid group, a sulfonic acid group, a heterocyclicgroup, an amino group, or a halogen atom, of which R₅ and R₆ may bebonded to each other to form a ring; X₁ ⁻ represents an anionic group;and A represents a formula (4):

where Y represents an alkyl group; and * represents a binding site; anddetecting in vivo the compound acting on the central nervous systemusing the administered central nervous system labeling composition. 3.The method according to claim 1, wherein the compound of formula (1) isa fluorescent compound.
 4. The method according to claim 1, wherein thecompound of formula (1) is labeled by a radionuclide.
 5. The methodaccording to claim 2, wherein the compound of formula (1) is afluorescent compound.
 6. The method according to claim 2, wherein thecompound of formula (1) is labeled by a radionuclide.